Well pipe

ABSTRACT

A well pipe having elongated slots which are bridged by webs of sheet material, a group of the slots being arranged longitudinally of the pipe and another group extending circumferentially.

Elite States atent [191 Stotzel et a1.

[451 Oct. 29, 1974 WELL PIPE Inventors: Friedhelm Stotzel,

Kreuztal-Ferndorf; Erwin Dobbeler, Welschen-Ennest; Voldemar Vaer, Kreuztal-Kredenbach, all of Germany Assignee: Schaubstahl-Werke, Kreuztal,

Germany Filed: July 26, 1973 Appl. No.: 382,744

Related U.S. Application Data Continuation of Ser. No. 164,327, July 20, 1971, abandoned.

Foreign Application Priority Data July 29, 1970 Germany 2037478 US. Cl. 166/227, 166/235 Int. Cl E2111 43/08 Field of Search 166/227, 233, 235; 61/11;

Primary Examiner-David H. Brown Attorney, Agent, or Firm-Norman S. Blodgett; Gerry A. Blodgett 5 7] ABSTRACT A well pipe having elongated slots which are bridged by webs of sheet material, a group of the slots being arranged longitudinally of the pipe and another group extending circumferentially.

4 Claims, 3 Drawing Figures PATENIED um 29 mm INVENTZORS FRlzonz ga g VOLDEMAR VAER ERWIN D WARM I ATTORNEY WELL PIPE This is a continuation of application Ser. No. 164,327, filed July 29, l97l, now abandoned.

BACKGROUND OF THE INVENTION The walls of well pipes are usually constructed with a number of holes shaped as elongated apertures positioned parallel to each other. They have their outer ends connected to the wall of the pipe by material pressed out of the wall and their long sides are free and extend parallel to the corresponding sides of the other slots. Such bridged-over slots have two openings per slot, so that the number of entrance openings is double that of normal perforations. An outstanding characteristic is that the strength of the well pipes is increased due to the pressed-out or staked web of material.

During fabrication of well pipes, the resistance to corrosion is not the only factor that has to be considered. The circular cross-section of the well pipe is exposed to considerable deformation during transportation to the site and, at the same time, has also been subjected to deflection. Large stacks of pipe with insufficient stability could bring about changes in crosssection and the demand for long pipes (which save connecting elements) leads to considerable bending stresses Also, tension, compression, bending, and buckling stresses are present during the connection and the installation of the well pipes, The same stresses may also be present due to rock pressure, etc., after installation of the pipes. Basically, the strength of the pipes may be increased by a larger, more expensive wall thickness. However, the resultant increased weight of the pipes causes the number of forces which are exerted on the pipe to grow. The necessary weakening of the walls because of the perforations may be at least partially compensated for by the bridging-over of the slots. The material web pressed out of the pipe wall increases the moment of resistance and, therefore, contributes to an increase of strength. In well-known well pipes these bridged-over slots are arranged parallel to each other in such a way that the direction of elongation of the slots and of the material webs pressed out of the holes run parallel to the length of the pipe, since by this arrangement the greatest stability is achieved. In special cases, the requirements for stability are lowered. For example, at a construction site it is common to use the so-called lost pipes which have a smaller wall thickness than the normal wall pipe and in which slotted holes are arranged which extend circumferentially of the pipe. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a well pipe having extraordinary resistance to deformation due to the forces encountered during storage, transportation, and use.

Another object of this invention is the provision of a well pipe having a large number of flow apertures without loss of strength.

A further object of the present invention is the provision ofa well pipe having a plurality of apertures, each of which is protected by a bridge of metal.

It is another object of the instant invention to provide a well pipe having a large number of slots which can be simply and inexpensively manufactured from readily obtainable materials by use of unskilled labor and which is capable of a long life of useful service with a minimum of maintenance.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

SUMMARY OF THE INVENTION In general, the invention has to do with a well pipe which has elongated holes or slots and with the same wall thickness shows increased stability. It will provide equal stability with a smaller wall thickness than commonly used in well pipes. This is achieved by arranging sections longitudinally of the pipe where one section consists of slots extending longitudinally of the pipe and the following section contains slots arranged circumferentially of the pipe. It has been found to be of advantage to make the length of the first slot section (with holes parallel to the pipe axis) a multiple of the length of the second pipe section (with circumferential- Iy-oriented slots). It has also been found to be of advantage to equip the second pipe section with up to six parallel rows of slots in the circumferential direction.

For practical purposes, the well pipes consist of at least three sections arranged longitudinally of the pipe, wherein the section having slots oriented circumferentially is positioned between two sections with the slots arranged longitudinally of the pipe axis.

BRIEF DESCRIPTION OF THE DRAWINGS The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a front elevational view of a well pipe making use of the principles of the present invention and having a threaded connection,

FIG. 2 shows a modified form of the well pipe having a flanged connection, and

FIG. 3 is an enlarged perspective view of a portion of the well pipe taken in the section III indicated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a well pipe 1 which is equipped on both ends 2 and 3 with threads to serve as a connection with other well pipes by means of couplings. The surface of the pipe 1 is perforated by bridged slots formed by punching or staking. As can be' seen in FIG. 3, showing an enlargement of a section III of the pipe wall, the slots 5 and the web 6 pressed out of the wall material are arranged parallel to the axis of the pipe and form a first section 4. The neighboring rows of slots are displaced by a half space. In the following shorter middle section 7 of a secondary type, the slots 8 and the webs 9 punched from the wall material are arranged circum ferentially. Following the short section 7 of the secondary type, a section 10 of the first type follows in which the slots and the webs are again arranged in the direction of the pipe axis. By means of the arrangement of the middle section 7 of the secondary type (which actually acts as a corrugated stiffener) a considerable increase of the moment of resistance of the pipe wall about its axis is achieved and with it a considerable stiffening of the pipe cross-section. In the case of the well pipe 1, it is sufficient to arrange. in the center one section 7 action as a cross-section stiffener. The two end portions of the well pipe are reinforced anyway by means of the couplings which are screwed onto the ends 2 and 3. The important parts of the pipe surface (namely the sections 4 and have the slots and webs arranged longitudinally of the pipe axis, so that they support the stability of the well pipe in the direction of the length. It has been found to be sufficient for achieving the desired cross-sectional stability to construct the second section with only a small width, which permits about two to six parallel rows of slots. For practical purposes, the neighboring parallel rows of slots are also displaced by a half space, as shown in the preferred embodiment.

It has been found that the arrangement of a single row of slots per section of the secondary type increases the cross-section stability somewhat and that an increase in the numbers of rows of slots to approximately six and more holes will result in a further crosssectional stability. However, at the same time, the longitudinal stability will suffer. In case of well pipes of great length or high cross-section stability requirement, the well pipe, for practical purposes, therefore, can be equipped not only with one section of the secondary type (as shown in FIG. 1), but will be equipped with several of these secondary sections.

FIG. 2 shows such a design in which two sections 14 of the secondary type are arranged between the sections 11, 12, and 13 of the first type. For higher re quirements, such as greater length of well pipe, a corresponding further sub-division with further sections of the secondary type can be arranged. Here also in the sections ll and 12 of the first type, the slots 5 and the webs 6 are oriented lengthwise of the axis of the pipe and the slots 8 and their webs 9 of the section 14 of the secondary type are oriented circumferentially of the well pipe.

For practical purposes, the sections of the first and second type are different considerably from each other in their length. On common designs, the sections of the first type are always the same length and the sections of the secondary type are also of the same length. The example shown in FIG. 2 is based on the fact that the sections 11 and 13 of the first type positioned at the ends receive a considerable stiffening by the connecting flanges l5 and 16. Based on this fact, the outer sections 11 and 13 of the first type are made longer than the middle section 12 lying between the end sections.

It can be seen, then, that the cross-sectional stability of a well pipe is considerably improved without the stability in the longitudinal direction being noticeably influenced. By the use of this invention, the well pipes receive a considerably higher cross-sectional stability by retaining the wall material, by retaining the wall thickness, and also by keeping the type of slotted perforations, as compared to the common well pipes and, therefore, they have a greater security against crosssectional deformations. Since the design and especially the wall thickness of prior art well pipes is often dictated by the need for cross-section stability, it is now possible to use pipes with a reduced wall thickness. Consequently, considerable material savings result and expenditures are lowered. The use of this invention is not limited to the use of certain materials; well pipes using the characteristics of this invention can be made from aluminum, copper, alloy, zinc, metal with protective plastic layers, or plastic itself. In every one of these cases, a desired higher stability is achieved compared to that available with the commonly designed well pipes.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent l. A well pipe equipped with a number of parallel elongated holes for the admission of water, the holes being designed in such a way that a pressed-out web of wall material bridges the hole and is attached to the wall at the ends of the hole characterized by the fact that the well pipe contains longitudinally-arranged alternate sections in which a first section has the elongated holes arranged with their lengths extending parallel to the pipe axis and a second section in which the elongated holes are arranged with their lengths extending perpendicular to the pipe axis. 2. A well pipe as recited in claim 1, characterized by the fact that the length of the first section is a multiple of the length of the second section. 3. A well pipe as recited in claim 1, characterized by the fact that the second section contains up to six parallel rows of holes. 4. A well pipe as recited in claim 1, characterized by the fact that the well pipe contains at least two sections with holes oriented along the pipe axis and between these sections a section is arranged wherein the holes are oriented circumferentially. 

1. A well pipe equipped with a number of parallel elongated holes for the admission of water, the holes being designed in such a way that a pressed-out web of wall material bridges the hole and is attached to the wall at the ends of the hole characterized by the fact thAt the well pipe contains longitudinally-arranged alternate sections in which a first section has the elongated holes arranged with their lengths extending parallel to the pipe axis and a second section in which the elongated holes are arranged with their lengths extending perpendicular to the pipe axis.
 2. A well pipe as recited in claim 1, characterized by the fact that the length of the first section is a multiple of the length of the second section.
 3. A well pipe as recited in claim 1, characterized by the fact that the second section contains up to six parallel rows of holes.
 4. A well pipe as recited in claim 1, characterized by the fact that the well pipe contains at least two sections with holes oriented along the pipe axis and between these sections a section is arranged wherein the holes are oriented circumferentially. 